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open cluster

A Dictionary of Astronomy | 1997 | Copyright

open cluster A group of stars formed together in the spiral arms of a galaxy; sometimes called a galactic cluster. Open clusters are usually irregular in shape and contain anything from a few dozen to several hundred relatively young stars in a volume up to 50 l.y. across. The Hyades and the Pleiades are well-known examples. Open clusters are divided into various types according to the Trumpler classification. They are more loosely packed than globular clusters, but may still have a central star density of up to 10 000 times that in the Sun's neighbourhood. Over a thousand are known, all in the galactic disk. Their ages range from a few million to several billion years, and the youngest are still surrounded by traces of the nebula from which they formed. The less dense of them are gradually disrupted by gravitational interaction with the rest of the Galaxy.

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open cluster

World Encyclopedia | 2005 | Copyright

open cluster (galactic cluster) Group of young stars in the spiral arms of our galaxy, containing from a few tens of stars to a few thousand. They are usually several light-years across. One example is the Pleiades.

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"open cluster." World Encyclopedia. 2005. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O142-opencluster.html

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open cluster

The Columbia Encyclopedia, 6th ed. | 2011 | Copyright

open cluster see star cluster .

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"open cluster." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1E1-X-openclus.html

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